1. Field of the Invention
The invention pertains to the field of polyurethane plastics and more particularly relates to polyurethane plastics made using novel polyester polymer polyols.
2. Description of Related Compositions
The use of a polyol in the preparation of polyurethanes by reaction of the polyol with a polyisocyanate in the presence of a catalyst and perhaps other ingredients is well known. Conventional polyols for flexible polyurethane foams are usually made by the reaction of a polyhydric alcohol with an alkylene oxide, usually ethylene oxide and/or propylene oxide, to a molecular weight of about 2,000 to 3,000 and above. These polyols are then reacted with polyisocyanate in the presence of water or other blowing agents such as fluorocarbons to obtain polyurethane foams. Polyols have been modified in many ways in attempts to improve the properties of the resulting polyurethane.
For example, elastomeric polytetramethylene ether polyurethane polymers may be made from reactions involving a polytetramethylene ether glycol having a molecular weight of at least 750, an organic diisocyanate and a chain extender containing active hydrogen according to U.S. Pat. No. 2,929,800. The glycol may be added to the diisocyanate to form a prepolymer.
U.S. Pat. No. 3,294,751 relates to the preparation of polyurethanes via a modified polyol called a ureido-polyol. These low molecular weight ureido-polyols are formed by the reaction of an organic compound consisting of a hydrocarbon group having less than 10 carbon atoms and at least one isocyanate group and an alkanolamine. Further, the invention disclosed in U.S. Pat. No. 4,118,376 concerns a hydrocurable composition suitable for use as coatings, adhesives or grouts. The composition contains oxazolidine compounds and free isocyanate groups containing prepolymers where the prepolymers are obtained by the reaction of polyisocyanates with special types of dispersions where the dispersed phase in synthesized in situ in a dispersing media of polyhydroxyl compounds.
Other prior art describes modified polyols in which vinyl monomers such as styrene or acrylonitrile or other materials such as hydrazine hydrate have been included to improve the properties of the polyols and thus, the properties of the resulting foam. However, some of these prior art materials are highly toxic and require, in addition, stripping of unreacted vinyl monomers or water of hydration.
German Offenlegungsschrift No. 2,110,055 discloses a process for making a polyurethane product whereby a hydroxyl-containing amine is included in the formulation in a one-shot process. That is, the hydroxyl-containing amine is simply included initially with the polyol and the polyisocyanate and a polyurethane product results. The German process does not use a polyurea polymer polyol which is then reacted with a polyisocyanate. Our invention makes improved polyurethane foams over the process of the German patent as will be made clear by the disclosure and the examples which follow.
A polymer-modified polyol may be formed by polymerizing an alkanolamine with an organic polyisocyanate in the presence of a polyol as taught by British Patent application No. 2,072,204A. The alkanolamine may react polyfunctionally with the polyisocyanate to produce polyaddition products which may constitute a stable dispersion in the polyol. The resulting modified polyol is stated to be particularly useful as a polyol starting material for reaction with a polyisocyanate in the manufacture of polyurethane foam.
Stable dispersions are also revealed in U.S. Pat. No. 4,089,835. Here, the stable dispersions comprise polyureas and/or polyhydrazo-dicarbonamides as the disperse phase in a hydroxyl group-containing material selected from the group of polyethers, polyesters, polyester amides and polycarbonates. These dispersions may be produced by reacting organic polyisocyanates with polyamines containing primary and/or secondary amino groups and/or hydrazines and/or hydrazides in the hydroxyl-containing material.
Similar polymer polyols prepared in the presence of water to reduce viscosity are taught as being useful in high resilience (HR) foams, according to U.S. Pat. No. 4,093,569. In this patent description, low viscosity dispersions are produced by reacting organic polyisocyanates with compounds having primary and/or secondary amino groups and/or primary hydroxyl groups in compounds having at least one hydroxyl group in the presence of more than 4% by weight of water.
An equilibrium product of two polyols, at least one of which is a polyester polyol, can be accomplished by heating the components at 230.degree. C. in the presence of tetraisopropye titonate as a catalyst. This equilibrium product is taught by U.S. Pat. No. 3,666,724 as a co-polymer which gives a better resulting foam.
Highly related is our own U.S. Pat. No. 4,296,213 which relates to polyurea polymer polyols made by the reaction of a hydroxyl-containing amine, a polyether polyol of about 3,000 to 8,000 molecular weight and an organic polyisocyanate. The hydroxyl-containing amines contemplated therein are described as ranging in molecular weight from about 60 to 200, preferably from about 60 to about 150. It was not realized that higher molecular weight, hydroxylcontaining amines, which also contain aromatic groups, would also give a polymer polyol which would impart enhanced properties to flexible urethane foams.